Instruments

To assess the convergent and discriminant validity of the I.ROC, five additional questionnaires were administered to the participants in the main study as follows:

There was a general questionnaire about participants’ demographic characteristics, including their age, sex, and primary diagnosis (as determined by the healthcare professionals who were involved). It was administered only at baseline; all of the other questionnaires were administered at each of the assessment points.

The Manchester Short Assessment of quality of life (MANSA) is a quality-of-life measure which comprises 12 questions [26]. The MANSA has been shown to have good psychometric properties and has been used regularly in research studies, internationally and in the Netherlands [27]. Respondents’ answers are summed to yield a single total score.

The Recovery Assessment Scale (RAS) is the most frequently used questionnaire for measuring personal recovery [18]. It has been shown to have good psychometric properties [28]. Several formats of varying length have been proposed; in this study we used the original version, which includes 41 questions. Questions are answered on a five-point Likert scale, ranging from 1 (Strongly Disagree) to 5 (Strongly Agree). Individual questions are summed to give a total score, and five sub-scale scores for the factors called: personal confidence and hope, goal and success orientation, willingness to ask for help, reliance on others, and no domination by symptoms [29].

A single question, which was adapted from the Pharmacotherapy Monitoring and Outcome Survey (PHAMOUS) [30], was used to measure on a seven-point Likert-scale the amount of physical exercise that participants engaged in. The PHAMOUS was chosen because we needed to measure physical exercise in order to validate the I.ROC question about physical exercise, which is not included in any of the other instruments in the test battery. There is however a difference between both questions. The exercise question from PHAMOUS is about the number of days per week where the participant is physically active (moderate-intensively; increased heart-rate, getting warm), the physical exercise question from the I.ROC asks the participant to judge their own level of physical activity.

The final questionnaire was the Outcome Questionnaire (OQ-45), which is an instrument that has been frequently used both clinically and in scientific research [31] to measure symptoms of mental illness and social functioning and was selected for this study because the Dutch version is extensively researched and validated [32]. The OQ-45 has 45 questions that are answered on a 5-point Likert scale. Responses are summed to yield a single total score and scores on three sub-scales: interpersonal relationships, social roles, and symptomatic distress.

The participants included in the additional data collection from routine measurements completed only the I.ROC and the OQ-45 questionnaires. All questionnaires were completed by all participants as an online self-report without assistance.